1. Field of the Invention
The present invention concerns an improvement for a microwave melting furnace for or treating liquid.
2. Description of the Prior Art
Heating and melting treatment for non-metal materials by utilizing a dielectric heating phenomenon caused by the irradiation of a microwave has been generally used with an aim of disposing various kinds of industrial wastes and radioactive wastes in the form of liquid or slurry as a so-called volume reduction or recovery of variable materials. The treatment by the irradiation of the microwave is conducted by introducing a microwave from a microwave oscillator by way of a waveguide tube to the inside of a furnace, matching the microwave by a tuner disposed in the upper portion and the waveguide tube portion at the inside of the furnace, as well as supplying materials to be treated such as incinerated ashes or sludges to the inside of a heating and melting crucible (generally made of metal).
In the microwave melting furnace, a metal crucible is mounted in a furnace body for heating the material to be treated and the material to be treated is supplied continuously into the crucible or charged by a predetermined amount and heated and melted batchwise. A microwave heating and melting furnace of the prior art has a constitution, for example, as shown in FIG. 6. In the figure, an upper furnace body 2 and a lower furnace body 3 are joined to each other by means of a flange 30 in a sealing structure, and the lower furnace body 3 is supported by a jack 4 on a wagon 40. The upper furnace body 2 has a metal waveguide tube 9 connected for introducing microwaves generated from a microwave oscillator not illustrated and also has a hopper 7 supplied by way of a screw feeder 8 for storing material to be treated such as incineration ashes. A protection vessel 5 is mounted at the inside of the lower furnace body 3 and a crucible main body 1 inside of the protection vessel 5 being supported by a flange 10 formed at the upper end thereof. The crucible main body 1 and the protection vessel 5 can be detached easily from the lower furnace body 3 by raising them upward, respectively.
In the constitution described above, the material to be treated containing a salt such as NaNO.sub.3 dissolved in a liquid or a liquid such as a sludge suspended therein is treated as shown below.